Method and apparatus for applying powdered materials to filaments

ABSTRACT

The present invention is directed towards a method and apparatus for treating materials consisting of a plurality of monofiliments with a treating agent. The treating agent is suspended in streams which are directed to the material from various directions and under a controllable pressure so as to separate the monofiliments and thereby expose the individual monofiliments to the treating agent. The streams of treating agent are directed to the material with application of the Venturi principle. The streams of treating agent may be applied in a reciprocating manner.

The invention relates to a process and a device for treating threads,slivers or the like consisting of various filaments and optionallyprocessed in a tissue or knitwear with a treating agent, a separationbetween the filaments being effected in order to have the agent betterpenetrate into the structure of filaments.

Similar processed and devices are generally known, in particular for theproduction of composed materials consisting of thermoplastic orthermosetting substances, wherein filaments function as reinforcingmaterial. For instance in Dutch patent application No. 70 01623 aprocess is described, wherein the threads of slivers consisting of agreat number of filaments are separated before a synthetic resin inpowder form is applied thereon, whereupon this resin is molten in resultof which a coherent product is obtained. The spreading of the filamentsin the slivers is for instance effected according to the Dutch patentapplication by giving to the filaments an electrostatic charge with thesame sign. According to another embodiment the slivers are passedthrough a venturi, which in the same direction is passed by a fluid at ahigh velocity. The spreading of the filaments occurs then under theinfluence of the relaxation of the fluid on leaving the venturi.

The invention provides for a process as mentioned in the preamble, whichis characterized in that the treating agent is suspended in one or moregas or liquid streams which are then directed to the material to betreated under controllable pressure.

It has turned out that in this way a very efficient spreading of thefilaments is effected, as a result of which impregnating materialsuspended in the streams of fluid penetrates well between the filamentsand impregnate same very homogeneously. This results in the finalproduct, for instance a sheet of plastic material reinforced byfilaments, being of a very homogenous composition.

The process according to the invention is applicable no matter what thenature of the filiments or the nature of the impregnating agent is.

For instance, powdery cermic products and metal products are consideredas impregnating materials in addition to thermoplastic or thermosettingmaterials.

The process according to the invention is also feasible for theapplication of layers of impregnating material of various thicknesses onvarious sides of the material to be impregnated. For instance a tissueor knitwear which is applied internally or externally to a lightweightcore can be impregnated by application of the invention.

As treating agent a grinding material can also be used, which makes thematerial treated with it rough, in result of which it is made bettersuitable for the adherence to it of a sizing and the like.

It is preferred to direct the gas streams wherein the treating materialis suspended with applications of the venturi principle to the materialto be treated.

The treating material can be suspended in a gas stream in various ways,for instance by atomizing it in the gas stream as a melt or liquid. Itis also possible to dose a powdery treating material directly into a gasor liquid stream from a container. It is also possible to suspend thetreating material in a fluidized bed in a gas and to withdraw the gasstreams to be directed to the material to be treated from the fluidizedbed by suction power. Per se the application of a fluidized bed for theimpregnation of bundles of filaments is known, for instance from Dutchpatent specification 151 928. In this known method, however, thematerial to be impregnated is passed through the fluidized bed ofimpregnating material.

If , however, in the process according to the invention a fluidized bedis applied, the actual impregnation occurs outside this bed.

The invention also relates to a device for carrying out the inventedprocess with a space wherein via a perforated bottom a gas can be fedand a supply-pipe for powdery treating agent, said device beingcharacterized in that the said space is provided with one or moresuction pipings, which on the discharge side debouch into means whichare reciprocable movable transversely to the path which the material tobe treated covers during operation of the device. If the gas is directedto the material to be treated from various sides, care can be taken thatthe gas streams do not fully collide with each other.

It is also possible, applying the invention, to apply variousimpregnating materials, either over each other, or to various faces, inseveral spaces separated from each other, in order to prevent anundesirable mixing of the various impregnating materials.

The invention will be illustrated hereinunder by way of example with theaid of the following description as well as the enclosed figures.

FIG. 1 is a side view in cross-section of a schematically drawninstallation for carrying out the process.

FIG. 2 is a top view of the device according to the invention.

FIG. 3 is a side view of the very same device.

FIG. 4 is a cross-section A.A of the very same device.

FIG. 5 is an enlarged representation of an essential part of the deviceaccording to FIGS. 2, 3 and 4.

FIG. 6 gives a number of variants a-e incl. of the application of theinvention.

As represented in FIG. 1 widths of continuous filament beams 1 areformed by unwinding them from the horizontal coils 2 under automaticallymaintained controllable tension. Via the guiding 3 the bundles come intothe preheating oven 4. The oven is heated with the automaticallycontrollable heat source 5. Then the dried and preheated filament beamsare passed through a thermally isolated receptacle 7, via the guiding 6,where impregnation takes place (FIG. 2-6 incl.). Thereupon the bundlesare passed via the melting furnace 8, wherein one or more heating bodiesare applied controlled by thermocouples. Same are automaticallycontrolled by the means 9 at a predetermined heating intensity.Thereupon the filament bundles are formed into bands and passed througha cooling means 11 via cooled forming rollers 10 and wound on thecollecting coil 14 via delivering rollers 12 and the guiding 13. Thiscoil is driven by the electromotor 15. After the delivering rollers 12the band of filaments can also further be processed for instance bycutting it longitudinally and/or transversely.

The installation for carrying out the process can, if desired, becarried out wholly or partly vertically.

In the device according to FIGS. 2-5 incl. the bundles of filaments inthe thermally isolated impregnation receptacle 7 are distributed overthe rollers 16, which are postioned outside the feeding axes.

Optionally the axes of the rollers 16 are mounted pivotally about theshaft 17 pair-wise. This makes it possible that the bundles can bepositioned in the centerline when they are pulled into the device.Speading of the bundles over more than one layer of rollers, in thiscase two, facilities a better distribution of the filaments. Afterhaving passed the rollers the filaments are impregnated. The powderyimpregnating material which is fed from the dosing device 18, isfluidized in the bed 20 in gas 21 fed through the perforated bottom 19.

Preferably this gas is preheated. In the spaces 22 under the influenceof pumping action, gas streams wherein the impregnating material issuspended are sucked under controllable pressure from the fluidized bedto the impregnating heads 23, from which it is directed to thecontinuously moving bundles of filaments. In order to effect an optimalimpregnation the impregnating heads 23 are optionally adjustable withrespect to distance and/or angle turning in regard of the material to beimpregnated.

The various parts which are applied in the impregnating receptacle 7 cansimply be displaced and/or replaced. For instance other types orrollers, and/or other impregnating heads can be used for theimpregnation of various types of material.

The gas streams with therein the finely divided impregnating materialare preferably directed to the filaments to be impregnated from two ormore impregnating heads. This results in a very homogeneous distributionof the impregnating material over the individual filaments. Theimpregnating method described makes it possible to operate with aconsiderably lower filament tension then required in a mechanicalimpregnating system, in which the impregnating material is pressedbetween the filaments by means of pressure rollers. The lower filamenttension results in the substantial elimination of filament rupture whichoften occurs in the mechanical impregnation of for instance carbonfilaments. This combined with the more intensive impregnation also makesa greater impregnation rate possible.

In FIG. 5 it is indicated that the suction of the gas wherein theimpregnating material is suspended occurs through the conduit 26 withapplication of the venturi principle. Via the conduits 25 gas is fedunder a controllable pressure. It is preferred to suck the gas fed by apump through the conduit 25 from the space 7.

In result a circulation pump system of the gas is obtained and heatlosses are prevented.

If no use is made of a fluidized bed it is advantageous to connect thedosing device 18 directly to the impregnating heads or their supplymains.

When using impregnating liquids it is preferred to inject the liquideither directly into the impregnating head(s) or to suck it directlyfrom the dosing device 18.

In FIG. 6 a plurality of schemes of embodiments of more-sided and/ormobile impregnating heads are represented, which are suitable for thecontinuous impregnation of bundles of filaments optionally processed ina tissue or knitwear. These bundles are optionally applied to cores.These may have the following shapes:

a. rectangular,

b. cylindrical,

c. honeycomb-shaped.

For the internal impregnation of hollow structures fully closed alongtheir circumference, which are provided with filament materials, theprocess must be discontinuous. Then impregnating heads can be applied inthe hollow spaces. Then the impregnating heads and/or the material to beimpregnated can be moved in such a way that the desired impregnation isattained. This is further illustrated with the aid of FIGS. 6e and d.

FIG. 6 d represents an aeroplane nose 27, which internally andexternally is provided with filament material that has to beimpregnated. For the internal impregnation use is made of theimpregnating head 28 and for the external impregnation of theimpregnating head 29. By rotating the nose and reciprocate theimpregnating heads 28 and 29 over guidings 30 and 31 the desiredimpregnation is obtained.

In FIG. 6e 32 represents part of a dish antenna internally andexternally is provided with filament material that has to beimpregnated. This occurs by means of the impregnating heads 33 and 34,which are reciprocated radially via guidings 35 and 36. If desired, themotions described can be computer controlled, which makes possible anoptimal impregnation of more complex types of material.

If bundles of filaments processed into tissues or knitwears are appliedto cores, the impregnated material is heated in an autoclave under apredetermined desired pressure. Optionally, heat emitters can be builtin in the autoclave.

According to the afore-described way impregnated filament bandsoptionally woven into a certain shape can be treated to aeroplane noses,radar domes and other structures. It is also possible to apply a meltingfurnace consisting for instance of two mould halves for heating.

In order to facilitate weaving, knitting and/or twisting withimpregnated filament bands can be separated wholly or partly intonarrower bands. These narrow bands are then provided with an additionalthin imprenating layer with application of the process according to theinvention. This layer consisting of a specially selected impregnatingmaterial sees to it that the impregnating material already presentbetween the filament remains in place during weaving and/or knitting andbesides prevents the adsorption of moisture. In order to effect this theband may optionally be subjected to for instance a temperature treatmenton the surface. Particularly in case of impregnating materials of highrigidity the weaving and/or knitting with narrow bands, which have notbeen passed through a melting furnace, is possible without aconsiderable adaptation of the installations in question and loss ofvelocity. Then the tissue, knittwear and/or twisted material can bepassed through a melting furnace in order to be processed furtheroptionally via cooled form rollers.

As treating agents may for instance be used:

Acetal resins

Acrylic resins

Acrylonitrile-butadiene-styrene resins

Aluminium

Alkyd resins

Aluminia

Aryl resins

Bismaleimide resins

Cobalt

Copper

Ekonol

Epoxy resins

Fluorcarbon resins

Fluorcopolymers

Lead

Melamine resins

Nickel

Phenol resins

Polyacetal resins

Polyacrylate

Polyamide (nylon)

Polybutadiene

Polybutylenterephthalate

Polycarbonate

Aromatic polyesters

Thermoplastic polyesters

Polyetheretherketones

Polyetherimides

Polyethersulfones

Polyalkenes

Polyethyleneterephthalates

Polyimides

Polyoxymethylen resins

Modified polyphenylene oxides

Polyphenylene sulfides

Polyphenylene sulfides

Polyphenylenoxides

Polyphenylsulfones

Polystyrene

Polysulfone

Polytetrafluorethylene

Polyurethane

Polyvinylchloride

Polyvinylidene fluoride

Modified polypropylene oxide

Silica

Silicon carbide

Silicon nitride

Silicone

Styrene acrylonitrile copolymers

Styrenic copolymers

Titanium

Tungsten

Urea

Vinyl ester

Rubbers

and additives like:

Anti static agents

Blowing agents

Colorants

Concrete

Coupling agents

Fillers

Flame retardants

Form materials

Heat stabilizers

Hollow fillers

Lubricants

Minerals

Plasticizers

Processing aids

Silicones

Stabilizers

Superalloys

Ultraviolet absorbers

Water soluble plastics

Whiskers.

The material to be treated may for instance consist of:

Aluminium

Aluminium oxides

Aramide

Asbestos

Boron

Carbon

Colbalt

Copper

Glass

High silica and quarz

Lithium aluminium silicate

Magnesium

Nickel

Polyalkene

Silica

Silicon

Silicon carbide

Silicon nitride

Steel

Titanium

Tungsten

Zinc

Zirconia

Zirconium.

I claim:
 1. A process for treating material consisting of a plurality ofmonofilaments with a powder treating agent, characterized in that thetreating agent is suspended in a fluidized bed in a gas stream and thatat least one stream of powder to be directed to the material to betreated is withdrawn from the fluidized bed by suction power and is thendirected to the material to be treated under a controllable pressure, soas to separate the monofilaments and thereby treat the separatedmonofilaments with the treating agent.
 2. A process according to claim1, characterized in that, the stream is directed to the material to betreated with application of the venturi principle.
 3. A processaccording to claim 1, characterized in that a plurality of streams aredirected to the material to be treated from various sides, and saidstreams do not fully collide with each other.
 4. A process according toclaim 1, characterized in that the means from which the stream flows tothe material to be treated is moved over this material in areciprocating manner.
 5. A process according to claim 1, characterizedin that the treating agent is directly fed to the stream directed to thematerial to be treated in dosed amounts.
 6. A process according to claim1, characterized in that the treating agent is an impregnating agent. 7.A process according to claim 1, characterized in that the treating agentis a grinding agent for making rough the material treated with saidagent in order to make the material better suitable for adherencethereon of additional agents.
 8. A device for treating materialsconsisting of a plurality of monofilaments, with a treating agent,comprising:means for guiding said material through a substantially openspace; means for supplying at least one stream containing a treatingagent to said materials in said open space so as to separate saidmonofilaments and thereby expose each monofilament to said treatingagent; said means including a suction pipe having a discharge end fordebouching said treating agent into said open space; and reciprocablemeans for debouching said treating agent over a path through which thematerials travel.